Design of an illuminated keyboard solves the problem of being unable to clearly identify characters and notations on the keycaps in a dark environment by computer users. The design mainly focuses on improvements in light transmission structure and keycap structure in the keyboard. Compared with the light transmission structure, the keycap structure is easier in improvement. The keycap in a conventional illuminated keyboard usually has a light mask layer coated on the press surface thereof and a plurality of transparent zones on the light mask layer to allow light to pass through. The transparent zones usually are a character or notation to enable users to identify in the dark environment.
R.O.C. patent No. M405001 discloses an illuminated keycap which comprises a casing stuffing layer, a base color layer, a notation layer, a light emitting layer and a protective layer. The casing stuffing layer contains a stuffing material. The base color layer covers the upper surface of the casing stuffing layer. The notation layer covers the base color layer. The light emitting layer contains light emitting material and covers the base color layer and contacts the notation layer directly. The protective layer covers the upper surface of the casing stuffing layer and can be made of a transparent material. The light emitting layer contains at least one type of light emitting material, such as fluorescent or phosphorous material which can absorb light and energy thereof to excite electrons from a ground state to an excited state, and radiate energy in the form of light, thus the light can illuminate the notations in the notation layer for a prolonged period of time. However, as the base color layer is monochromatic and looks dull and humdrum, and the light emitted directly through the top surface of the keycap is too strong, users are difficult to identify the individual keycaps and easy to make errors when entering characters or commands that result in repetitive input entry. After being used for a prolonged period of time, users' eyes easily feel fatigue or even cause vision injury if the users try very hard to identify the notations on the keycaps.
In order to increase diversity of the keyboard, China patent No. CN 202258936U provides a dual-color keycap. It includes a cap body formed via plastic injection and a coated layer on the outer wall of the cap body and in a color different from the cap body. The dual-color keycap thus formed provides a multi-layer visual feeling. But its coated layer is formed by spraying. Thus the top surface of the cap body has to be covered prior to spraying. Moreover, the color sprayed on the coated layer is different from the cap body, hence spraying is a tedious and time-consuming that increases the production cost and is not economic. There are still rooms for improvement.